The present invention relates to a retaining device suitable for holding an object in a desired position.
Such retaining devices typically comprise a clamping device having a pair of jaws which enclose a cylindrical bore. An object may be retained in the cylindrical bore by tightening a clamping bolt which is in screw threaded engagement with both of the jaws of the clamping device. Such a device is disclosed in European Patent No. 0508686.
The above-mentioned retaining device has the disadvantage that as the clamping device is tightened, the object to be retained is pushed slightly to one side. This movement is caused by the unsymmetrical forces applied on the object by the clamping device which tends to xe2x80x9cpinchxe2x80x9d the object. If the clamping device is rigidly secured to a base of the retaining device, this increases the tendency of the object to be moved on tightening of the clamping device.
According to a first aspect of the present invention a retaining device for releasably retaining an object in a fixed position comprises:
a holder into which the object is inserted;
a clamping device which surrounds the circumference of the holder, which when tightened applies forces at symmetrical points around the circumference of the holder which in turn transmits symmetrical clamping forces to the object;
wherein the holder is a deformable tube and deforms in shape when the clamping device is tightened.
According to a second aspect of the present invention a retaining device for releasably retaining an object in a fixed position comprises:
a holder into which the object is inserted;
a clamping device which surrounds the circumference of the holder, which when tightened applies forces at symmetrical points around the circumference of the holder which in turn transmits symmetrical clamping forces to the object;
wherein an object to be inserted into the holder is provided with a spherically shaped portion such that the object may be angularly adjusted about all three axes inside the holder until the clamping device is tightened to fix the object in position.
According to a third aspect of the present invention a retaining device for releasably retaining an object in a fixed position comprises:
a holder into which the object is inserted;
a clamping device which surrounds the circumference of the holder, which when tightened applies forces at symmetrical points around the circumference of the holder which in turn transmits symmetrical clamping forces to the object;
wherein the clamping device has an inner surface comprising a plurality of recessed lobes located about the longitudinal axis of the holder, wherein only those portions of the inner surface between adjacent recessed lobes are in contact with the holder, and wherein those portions of the inner surface in contact with the holder are arranged symmetrically about the longitudinal axis of the holder.
According to a fourth aspect of the present invention a retaining device for releasably retaining an object in a fixed position comprises:
a holder into which the object is inserted;
a clamping device which surrounds the circumference of the holder, which when tightened applies forces at symmetrical points around the circumference of the holder which in turn transmits symmetrical clamping forces to the object;
wherein the clamping device comprises a U-shaped portion which surrounds the circumference of the holder and wherein the two arms of the U-shape may be pulled together to tighten the clamping device.